One-game playoff

From BR Bullpen

A One-game playoff is an extra game tacked on to the end of the regular season to determine which of two teams who have finished with the same record get to advance to the postseason. Statistics from such playoff games are counted with regular-season statistics. A playoff is only used when there is only one spot available in the postseason for the two teams; in cases where one team will make the postseason as the division winner and the other as the wild card, tiebreakers are used to determine which team earns which spot.

The American League has always used a one-game playoff to settle who will advance in these situations. Prior to the advent of divisional play in 1969, the National League used a three-game playoff to settle entry into the World Series. With the adoption of divisions, however, the NL switched to a one-game playoff format as well.

American League one-game playoffs:

National League one-game playoffs: